Not Applicable
Not Applicable
1. Field of the Invention
The present invention relates to scorelines for a face of a golf club. More specifically, the present invention relates to stress reducing scorelines for a golf club.
2. Description of the Related Art
Scorelines have appeared on the faces of golf club heads since at least the 1880s if not earlier. Scorelines usually have a cross-section that is square or slightly curved on the walls perpendicular to the face.
However, scorelines act as a stress concentrator during impact of the club face with the golf ball. For the most part, this has been of little concern since the thickness of the face has been great enough to absorb the stress concentration caused by the scorelines. However, with the advent of hollow metal woods, stress has become of concern in the face of the club head. As the thickness of club heads become thinner, the need to relieve some of the stress concentration caused by scorelines will present a problem for the golf club industry.
The Rules of Golf, established and interpreted by the United States Golf Association (xe2x80x9cUSGAxe2x80x9d) and The Royal and Ancient Golf Club of Saint Andrews, set forth certain requirements for scorelines. The requirements for scorelines (grooves) are found in Rule 4 and Appendix II. A complete description of the Rules of Golf are available on the USGA web page at www.usga.org. Rule 4-1e of the Rules of Golf state specific guidelines for scorelines. The impact area of a club face may have a series of grooves with diverging sides and may have a symmetrical cross-section. The width and cross-section must be consistent across the face and along the length of the grooves. Any rounding of the groove edges shall be in the form of a radius which does not exceed 0.020 inches, and the width of the grooves shall not exceed 0.035 inches using the 30 degree method of measurement on file with the USGA. The distance between edges of adjacent grooves must not be less than three times the width of a groove, and not less than 0.0075 inches. The depth of a groove must not exceed 0.020 inches. Punch marks may be used if the area of such punch mark does not exceed 0.0044 square inches. A punch mark must not be closer to an adjacent punch mark than 0.168 inches measured from center to center. The depth of a punch mark must not exceed 0.040 inches. If punch marks are used in combination with grooves, a punch mark must not be closer to a groove than 0.168 inches measured from center to center.
One aspect of the present invention is a golf club head including a face having a plurality of line scorelines. Each of the plurality of line scorelines has a contour with a continuous curvature. The face has a thickness that is less than 0.110 inches.
The contour of each of the plurality of line scorelines may have a first convex section, a concave section, and a second convex section. The greatest depth of each of the plurality of line scorelines may be less than 0.008 inches. The face may include a heel portion, a toe portion and a center portion juxtaposed by the heel portion and the toe portion, wherein the center portion is divided into a crown half and a sole half, and the crown half has an absence of line scorelines. The heel portion and the toe portion of the face may have an equal number of line scorelines. The vertical distance between each of the plurality of line scorelines may be equal. The width of each of the plurality of scorelines may be between 0.028 and 0.032 inches. The face may have a thickness in the range of 0.064 to 0.110 inches. The golf club head may be a metal wood and may be composed of a material selected from the group consisting of a forged titanium alloy material, steel, composite materials, and mixtures thereof. Alternatively, the golf club head may be an iron or a putter with a relatively thin face having the plurality of line scorelines thereon.
Another aspect of the present invention is a golf club head including a face having a plurality of line scorelines. Each of the plurality of line scorelines has a depth less than 0.012 inches and a contour including a first convex section, a concave section and a second convex section, with the face having a thickness that is less than 0.110 inches.
Yet another aspect of the present invention is a golf club head including a face having a plurality of line scorelines. Each of the plurality of line scorelines has a contour including a first convex section, a concave section and a second convex section, with each of the plurality of line scorelines having a depth that is greater than twenty percent of the thickness of the face. Thus, the depth of each of the line scorelines is substantial compared to the thickness of the face.
Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings.